Demystifying compost and muck

The news that there may be a permanent ban on outdoor fires in Taranaki has had me thinking. At first I thought it must only apply to urban areas but there was no mention of that in the early statements from Regional Council. Letter writers to the editor, who applauded the proposal and commented that with the increasingly efficient kerbside recycling services this should not be a problem for people, clearly lived in the city. And I would hazard a guess that they don’t have large gardens.

This is not to say that I am opposed to the idea of discouraging the burning of organic waste, but I am not sure that a blanket ban is the way to go. In a large garden with many trees, we have constant debris. Anything that can be, is composted through our series of compost mounds. Tree branches larger than about 10cm are cut up for firewood but there is all the twiggy stuff in between which up until recently we have dumped on the burning heap in a paddock. Our latest acquisition here is a good solid mulcher bought second hand on Trade Me (and voted by the one who uses it here as his second most favourite piece of machinery). This should eliminate the need for our annual bonfire but, like the chainsaw, mulchers have a petrol powered carbon footprint and are noisy. And mulchers are not going to suit all home gardeners. Nor does the mulcher solve the problem of rose clippings which I still incinerate.

But we would all be foolish not to heed the rumblings. The times they are a-changing and we had better start to think around some of the practices which are becoming increasingly unacceptable.

At the most basic level, the only people I consider justified in putting food scraps out in the rubbish are those who live in apartments with no outside garden. There is not a lot of point in loading landfills with plastic wrapped food en masse when it is very easy to dispose of at home.

So herewith the compost guide for beginners. The very mention of compost arouses passions in some, believe it or not. There are entire books and websites devoted to the topic and they can go into extraordinary technical detail requiring adherence to recipes, a strict timetable of rotation and turning, along with the construction of aerated bins. If you already manage compost in this manner, you do not need to be reading further.

But for beginners, there is compost and there is rotting. Compost is dryish, light, full of air and does not smell. It has been naturally heat treated. Rotting is often pongy, sludgy and heavy. It has not generated heat.

Rotting is fine in some cases and easy to manage. Rather than (horror of horrors) raking up the autumn leaves and burning them, to the detriment of neighbours’ washing and the environment, you can rake them back under the bushes and let them break down naturally. After a few months, you have what is called leaf litter and it is inoffensive, fertile and fine for raking back over the garden beds as mulch.

Kitchen waste is often rotted, rather than composted. In fact the simplest method can be to start a trench in the vegetable garden and bury the scraps, covering them with the soil from the next part of the trench as you work your way along. The worms will then break down the food and it doesn’t take long before you can use the row for planting. The major disadvantage is dogs and you don’t want to be burying meat.

While we have a row of proper compost mounds, they are some distance from the kitchen so we use one of those useful black bins with no bottom in it for food scraps. It looks tidy in the vegetable garden and keeps the dogs out though rats can burrow beneath. We refer to it as the compost bin but in fact the contents are rotted, not composted. We avoid putting any weeds which are seeding in there or any diseased vegetable waste because rotting alone does not kill seeds and fungi. Leaf litter would be fine in one of these black bins if you like to keep the garden tidy. Mark rakes out the contents into the vegetable garden from time to time. Rotting does not have to be unhygienic and in fact you can encourage your own worm farm to do the breaking down for you.

Proper compost is something else entirely. In smaller gardens it is tidier to work on constructed compost bins so you start in one bin, fork it into the second bin (this is aerating it), adding nitrogen if required, and then into the third bin from where you use it for the garden after a few months. We have a large amount of green waste here and sufficient space to manage free form mounds which get turned by the front end loader on the tractor but in days gone by, (before the advent of our baby tractor) Mark used to fork it all over as required. If you are past forking compost, there are more expensive rotating bins on the market.

The whole principle of composting is to generate aerobic action and heat which is what purifies the compost. We all know about grass clippings heating up and steaming but without the addition of air, roughage and carbon you are actually creating something more akin to smelly, fermented ensilage.

Compost aficionados have recipes, not unlike cooking, but we have never felt the need to be so regimented. We pile all the waste into heap number one, grass clippings and all. When the heap is large enough, it gets turned and sprinkled with nitrogen in granular form. If you have chickens, this is the point at which you add chicken manure as a natural source of nitrogen. If you have a lot of grass clippings, they also provide natural nitrogen. Some people like to bring in seaweed or other animal manure at this time but we have quite enough of our own waste, thank you, without needing to gather it up from other sources. The nitrogen is important because that is what starts the aerobic action and the heat which is the all important part to kill the unwanted greeblies. It is now heap number two.

Ideally number two should be turned a second time a week later to keep the composting action in full swing. We turn each mix several times but twice is the minimum. We then cover it with black plastic and leave it for a couple of months before using it, mostly as a garden mulch but also to add goodness and a lighter texture when planting trees and shrubs. We favour a pretty dry mix here. Done properly, it is weed free and clean to handle.

Apparently around 40% of what goes to urban landfill is green waste. If you can deal with it in your own garden, you will certainly be reducing your carbon footprint. Separating out green waste for recycling may be one step better than throwing it in with the polystyrene, plastic and tin but it still requires energy input for it to be collected or delivered and composted at the landfill before you then drive your vehicle to go and buy compost (often in plastic bags) to return to your garden. If you are serious about saving the planet, cut out the middle man and start working out ways to deal with your own green waste at home.